Samenvatting

Background: Predictive equations are often used to estimate resting energy expenditure (REE). Since body composition changes towards less fat-free mass (FFM) and more fat mass (FM) during aging, equations based on a younger reference population might not be accurate for overweight people over 55 years of age. Aim: To make a hypo caloric diet, the development of an accurate predictive equation in overweight people over 55 years of age was desirable. The objective was to evaluate the accuracy of current equations and develop a new predictive equation for this specific population. Methods: In this study, baseline measurements were performed in 81 subjects over 55 years of age with a body mass index (BMI) of ≥28 kg/m2 from different weight-loss studies. REE, weight, height, age, gender, FFM and FM were measured. REE was measured with a ventilated hood system (Vmax Encore n29), FFM and FM were measured using air displacement plethysmography (BODPOD Life Measurement Inc, Concord, CA). Measured REE was used as reference and compared with 69 predictive equations for estimating REE, of which 56 equations based on weight and height and 13 equations based on FFM and FM. By using linear regression techniques, new equations were developed. The accuracy of the REE equations was evaluated on the basis of the percentage within 10% of REE measured. Statistical techniques were used to evaluate the current equations in comparison with the newly developed equations: root mean squared error (RMSE), concordance correlation coefficient (CCC), Bland-Altman plots. Results: Accuracy of current equations and the newly developed equations were tested. When comparing predictive equations based on weight and height, Korth et al. (72.8% accurate prediction; RMSE 193; CCC 0.776) and the newly developed Klaver-Rootjes Gender equation (69% accurate prediction; RMSE 183; CCC 0.776) gave the most accurate values. The equation based on FFM and FM with the highest values of accurate prediction was the newly developed Klaver-Rootjes equation (70.4% accurate prediction; RMSE 178; CCC 0.792). Conclusion: The equations from Korth et al., Klaver-Rootjes, and Klaver-Rootjes Gender predicted REE most accurately in this study. To evaluate whether the Klaver-Rootjes equation is accurate in another overweight population, cross-validation is necessary. Key words: Resting energy expenditure, overweight, predictive equation, weight, fat-free mass